The invention relates to a multi-level laminating press to laminate essentially planar work pieces under the influence of pressure and heat, particularly photo-voltaic modules.
Accordingly, a multi-level laminating press of the present type comprises a number of hot plates arranged over top of each other and movable in reference to each other, with all the hot plates usually being moved simultaneously or in groups in order to open and close the press. If necessary, the hot plates can also be moved individually in order to open and close individual press chambers. Further, a multi-level laminating press of the present type comprises a number of conveyers with one upper run and one lower run each revolving around the hot plates. The work pieces are then inserted into the press by the traveling motion of the conveyers, supported on the upper run, and again removed therefrom.
A multi-layer laminating press of the present type also comprises sealing elements to form vacuum chambers in each space between a first hot plate and the respective second hot plate arranged adjacently thereabove when the press is closed, with the sealing elements being arranged between the hot plates and the conveyers. This means that either separate sealing elements are provided, or the conveyers themselves seal the hot plates. In a closed press the lower run of the second conveyer of the second hot plate is supported on the upper run of the first conveyer of the first hot plate, while the work piece to be laminated is arranged between the upper run of the first conveyer and the lower run of the second conveyer inside the vacuum chamber. The vacuum chamber may be evacuated and/or pressurized.
Laminating presses to laminate particularly photo-voltaic modules are known, for example, from WO 2006/128699 A2. An upper part with a sealing frame is arranged above the hot plate, with said sealing frame outlining a vacuum chamber, which can be evacuated when the press is closed by a tight contact of the sealing frame to the hot plate. A membrane is stretched over the sealing frame sealing the vacuum chamber and serving as a compression means in order to apply the pressure against the hot plate necessary to laminate the work piece. For this purpose, in a closed press the vacuum located under the membrane between it and the hot plate is evacuated causing the membrane to closely contact the work piece. If necessary, the pressure chamber, formed by sealing the sealing frame in reference to the upper press plate and limited towards the bottom by the membrane, is pressurized with compressed air. Particularly when laminating photo-voltaic modules it is very advantageous to operate with such membranes, because the modules usually exhibit an uneven surface. Additionally, it is of the utmost importance that the lamination occurs free of bubbles and no leaks develop through which moisture could enter the photo-voltaic modules.
In order to laminate photo-voltaic modules usually very strong adhesives are used. Therefore, it is common in prior art to protect the membrane by a separating film placed between the membrane and the work piece, because adhesive remnants on the membrane, which may render it useless or at least worsen its operation, can only be removed from the membrane using considerable efforts which are hard to justify.
Particularly in photo-voltaic modules having their yield of electric energy directly depending on their area, the processing capacity per surface area directly influences the cost efficiency for temporarily limited processes such as laminating. Accordingly it is advantageous to provide a multi-layer laminating press, in which several pressing layers are arranged over top of each other. In this way, the area capacity to be processed is increased without increasing the space necessary at the production site.
A multi-layer laminating press with individual layers of the above-described type is described in EP 1 609 597 A2. However, this fails to sufficiently solve the problem of the membranes sticking together; because separating films must be manually placed onto the work pieces to prevent this from occurring. Of course, this renders the process slower and more expensive, compromising the advantages of the multi-layer press.